Method of making and treating bias cut fabric

ABSTRACT

A fabric suitable for V-belt covers and hose reinforcing is made by bias-cutting a tubular woven fabric into a continuous strip, stretching the continuous strip in the width direction as with a pin tenter frame to increase the angle between warp and filling to greater than 90*, applying an elastomeric coating, and longitudinally slitting the strip into a plurality of narrower tapes which are then wrapped around a V-belt core in a conventional manner or used as hose reinforcing.

United States Patent 1191 Griffin 1 1 Jan. 8, 1974 [54] METHOD or MAKINGAND TREATING 1,905,916 4/1933 Leguillon 117/7 BIAS CUT FABRIC 1,323,21211/1919 Bulley 156/271 X Th2. 3,592,709 7/1971 Marzocchi et a1. 156/137[75] Inventor 'xz g if' FOREIGN PATENTS R APPLICATIONS 337,176 /1930Great Britain 156/137 [731 Asslgneel Burhngm" w' Inc-1 551,463 2 1943Great Britain 156/141 Greensboro, NC. 22 i June 3 1 PrimaryExaminerC1ifton B. Cosby App]. No.: 42,914

Att0rney-Cushman, Darby and Cushman [57] ABSTRACT [52] U.S. CI 156/139,77/233, 117/7, A fabric suitable for V-belt covers and hose reinforc-156/88, 156/141, 156/185, 156/229, ing is made by bias-cutting a tubularwoven fabric into 156/271, 156/308 a continuous strip, stretching thecontinuous strip in [51] Int. Cl B29h 7/22 the width direction as with apin tenter frame to in- [58] Field of Search 156/137, 141, 191, creasethe angle between warp and filling to greater 156/194, 195; 117/7;74/233 than applying an elastomeric coating, and longitudinally slittingthe strip into a plurality of narrower [56] References Cited tapes whichare then wrapped around a V-be1t core in UNITED STATES PATENTS aconventional manner or used as hose reinforcing. 2,519,590 8/1950Mitchell 74 233 x 6 Claims, 1 Drawing Figure (finer/72s A 9 [72 224225flf' 9a? i 11 A2 mamw raauzae 5400c i axe/P 0F 4 70 074 i)? 7 223222-73;

, A /6 t'l/fZ/A/f ay I 71" (T$ m z'azf a/wze; A P Y n/vsramre 4/1/0517METHOD OF MAKING AND TREATING BIAS CUT FABRIC This invention relates toindustrial fabrics for use as an outer protective fabric cover orwrapper for power transmission belts or as reinforcing for hoses, and inparticular it relates to a method of making a bias-cut woven fabric.

Power transmission belts such as V-belts generally include an outerprotective woven fabric cover bonded to a reinforced elastomeric core ofthe belt. Similar fabrics are employed as reinforcing in hose. Normallythe initial woven fabric is purchased in relatively broad widths and,after the application of a resinous and/or rubber composition, thefabric is cut on a 45 bias into relatively wide strips between 50 and 60inches wide. The individual strips are then lap spliced together byoverlapping the end of one strip with another approximately 5 inch,using the tacky rubber compound as an adhesive, and are then wound upinto the form of a roll 50 to 60 inches wide and perhaps 100 to 300yards long. The fabric is then slit longitudinally into relativelynarrow tapes of the desired width and length.

The threads in the tapes run at about 45 to the longitudinal dimensionof the tapes as a result of the initial bias-cutting step. When thetapes are used to wrap V- belts, the longitudinal dimension of a tape isaligned with the longitudinal axis of the belt core with the result thatthe angular disposition of the threads to the belt axis is also about45. This is highly desirable because, during flexing of the belt in useandthe concomitant extension of the belt core, the threads in the coverare displaced from their normal 90 angular relationship with each otherand therefore exert relatively little restraint on flexing of the belt.Analogous advantages are obtained when the bias-cut fabric is used asreinforcement in making hose.

More recently it has been suggested by belt makers that an angle ofgreater than 45 between the cover threads and the belt axis will providegreater flexibility, because during flexing of the belt the threads willbe pulled still further out of their normal relationship before theyexert their inex'tensible influence upon flexing of the belt. It will beunderstood that if the angle of both the warp and the filling withrespect to the longitudinal axis of the strip is to be greater than 45,then the angle between the warp and the filling must be greater than 90.

The present invention is directed to a method of making bias-cut stripsor tapes which does not require the splicing together of individualbias-cut fabric strips and which achieves a desired predetermined largeangle between the warp and the filling. These advantages are obtained,broadly, by bias-cutting a tubular woven fabric into a continuous strip,using a cutting angle of between 40 and 50 and controllably stretchingthe strip in its width direction to increase the angle between the warpand the filling to a predetermined angle greater than 90 and up to about160. The stretching operation may be carried out by overfeeding to apintenter frame which is adjusted to effect the desired stretch. The stripis then slit longitudinally into tapes of the desired width or woundinto a roll for subsequent use.

The accomplished angle should be stabilized, as by applying a resinand/or elastomer containing composition to the fabric at some point inthe process, so that subsequent handling does that the fabric willbecompatible with the rubber belt core material or ubber hose material towhich it is to be bonded. Preferably a liquid composition, such as awater-based resorcinol formaldehyde composition or a rubber cement, isapplied as by dipping prior to the stretching operation, and thecomposition is heat-cured after stretching to set the resin or evaporatethe solvent. It will be understood that the stretching operationinvolves an angular displacement of warp and filling relative to eachother, which is assisted by the lubricating properties of the appliedcompositions, but that no elongation of the threads occurs. A finalapplication of an elastomeric composition precedes the slitting of thestrip into tapes which are themselves, of course, free of splices.

The advantage of the spliceless fabric produced by the process of thepresent invention is that it avoids many of the problems associated withthe use of the conventional spliced fabrics, particularly in V-beltmanufacturing which at the present time involves a number of handoperations. For example, quality standards require thatno more than aspecified number of splices be present in a given belt. covering. Also,the presence of splices in the tape often produces a dog ear duringwrapping, due to separation of the spliced ends, and this requires thatthe cover be repaired or discarded and that the wrapping step berepeated. The spliceless fabric of the present invention is thereforewell suited to automation in wrapping V-belts, because there is no needto stop the wrapping machinery to repair separated splices.

The invention will be further understood from the following moredetailed description of an illustrative embodiment taken with the soleFIGURE which is a flow-sheet illustrating a process for making andwrapping V-belt covers.

As previously stated the first step of the process is to bias-cut awoven tubular fabric 10,, having warp 12 and filling 14, into acontinuous strip 16 of fabric of width W. The tubular fabric itself maybe woven in any conventional manner using, for example, threads ofcotton, cotton/nylon or cotton/polyester in conjunction with afour-harness loom or with a circular loom. Conventional equipment mayalso be used for the cutting operation, it being understood that suchequipment is capable of converting a woven tube into a single bias-cutstrip the length of which is related to the length and width of theinitial tube. The cutting angle should be 40 to 50, preferably 45, withrespect to the longitudinal axis of the tube. The initial tube may be,for example, 30 to 48 inches in flat width, and the cutting equip mentmay be adjusted to cut a strip 50 to 60 inches wide. The warp 12 andfilling 14 in the strip 16 will be at their normal relationship as inthe initial tube, or possibly a little less, and both'sets of threadswill lie at approximately 45 with respect to the edges of the strip.

In the preferred embodiment the bias-cut strip 16 is then coated orimpregnated with a binder composition which serves the purposes oflubricating the threads to assist in the angular change effected in thenext operation, stabilizing the adjusted thread angle and enhancingadhesion of the final elastomeric coating to the fabric. The compositionmay be any of the usual resinous binder compositions normally appliedtoV-belt fabric, such as a water dispersion of or a solution of resorcinolformaldehyde. The composition may also contain both not change the angleand so a resin and an elastomeric component such as neoprene, or it mayconsist solely of an elastomeric component in a solvent or as adispersion. Application of the binder composition is convenientlycarried out by running the strip 16 through a bath of the compositionand squeezing out the excess liquid.

The coated or impregnated strip 16 is then tensioned in the widthwisedirection, that is transverse to the longitudinal dimension, to increasethe angle between the warp and filling to a value above 90 and up to160. Generally an angle of 110 to 135 is preferred. The transversedimension of the strip 16 is actually increased when the relative threadangles increase, and in this sense the strip 16 is stretched, althoughthere is little or no elongation of the individual threads. At the sametime there will be a decrease in the longitudinal dimension of thestrip. The tensioning operation can be conveniently carried out byoverfeeding the strip in the longitudinal direction to a pin tenterframe, the overfeeding being necessitated by the just-mentioned decreasein length which accompanies the increase in width. As is well known, apin tenter frame includes a pair of spaced apart driven endless chainseach of which carries a series of pins 17 adapted to be attached to oneedge of a strip of fabric. In carrying out the present invention theangular disposition of the chains is adjusted to a predetermineddiverging angle in the direction of fabric movement so that acontrolled, predetermined stretch is imparted to the fabric. This inturn imparts a controlled, predetermined angular relationship betweenthe complementary threads in the fabric.

While the fabric strip 16 is still in the tenter frame or after it hasbeen removed, the binder composition is cured by heating the strip 16 toa temperature which is appropriate to cause the binder composition to'set and which is in part dependent on the dwell time in the tenter andon the nature of the fiber. For a resinous composition 300 to 425F issufficient to cause the resin to react, and for simple elastomericsolvent cements 120250F is sufficient to drive off the solvent. As amatter of convenience both may be referred to as curing. The warp andfilling are thus stabilized within the strip 16 so that subsequentoperations will not alter the thread angle which has been imposed.

After curing of the binder composition an elastomeric composition isapplied to the strip 16, and the latter is then slit longitudinally intoa plurality of tapes 16' of desired width T, for example 3 to 4 inches.The elastomeric composition may be any of those normally employed inimpregnating V-belt covers, such as a cement formed from neoprenedissolved in a solvent. The strip may conveniently be run through a bathof the cement and dried prior to slitting.

The coated tapes 16' may then be processed in the usual manner forV-belt covers or for hose reinforcing. As illustrated a length of tape16' is wrapped around a V-belt core 18 by first aligning thelongitudinal dimension of the tape 16' with the longitudinal dimensionof the core 18 and then folding the edges of the tape 16 around thecore. Following this the wrapped core may be cured in the usual manner.

I claim:

1. A process for making a continuous, spliceless strip of bias-cutfabric in which the angular displacement between warp and filling isgreater than 90, said process comprising: bias-cutting a woven tubularfabric at between 40 and-50 into a continuous strip of fabric; applyinga liquid curable binder to the continuous strip;

stretching the strip in its width direction to increase the anglebetween the complementary threads to greater than curing the bindercomposition to stabilize the angular positions of the threads; applyingan elastomeric coating to the strip; and slitting the striplongitudinally of itself into a plurality of long tapes.

2. A process as in claim 1 wherein the stretching step increases theangle of the complementary threads to between and 3. A process as inclaim 1 wherein said binder composition contains resorcinolformaldehyde.

4. A process as in claim 1 wherein said binder composition is selectedfrom the group consisting of disper sions of an elastomer in a carrierliquid and solutions of an elastomer in a solvent liquid.

5. A process as in claim 1 wherein the stretching step increases theangle of the complementary threads to between 110 and 6. In the processof making an elastomeric power transmission belt by wrapping a wovenfabric cover about an elastomeric core the improvement which comprises:bias-cutting a woven tubular fabric at between 40 and 50 to thelongitudinal axis of the tube to form a continuous strip of fabric;applying a liquid curable binder to the continuous strip; stretching thecontinuous strip in its width direction by applying lateral outwardforces to both edges of the strip simultaneously to thereby increase theangle between the complementary threads of the strip to 100 -l60; curingthe binder composition to stabilize the angular positions of thethreads; applying an elastomeric material to the continuous strip;slitting the continuous strip longitudinally of itself into a pluralityof long tapes each of which is of sufficient length to completely coverthe elastomeric core when wrapped therearound; and wrapping one of saidtapes, without splicing to another tape, around the elastomeric core.

2. A process as in claim 1 wherein the stretching step increases theangle of the complementary threads to between 110* and 135*.
 3. Aprocess as in claim 1 wherein said binder composition containsresorcinol formaldehyde.
 4. A process as in claim 1 wherein said bindercomposition is selected from the group consisting of dispersions of anelastomer in a carrier liquid and solutions of an elastomer in a solventliquid.
 5. A process as in claim 1 wherein the stretching step increasesthe angle of the complementary threads to between 110* and 160*.
 6. Inthe process of making an elastomeric power transmission belt by wrappinga woven fabric cover about an elastomeric core the improvement whichcomprises: bias-cutting a woven tubular fabric at between 40* and 50* tothe longitudinal axis of the tube to form a continuous strip of fabric;applying a liquid curable binder to the continuous strip; stretching thecontinuous strip in its width direction by applying lateral outwardforces to both edges of the strip simultaneously to thereby increase theangle between the complementary threads of the strip to 100* -160*;curing the binder composition to stabilize the angular positions of thethreads; applying an elastomeric material to the continuous strip;slitting the continuous strip longitudinally of itself into a pluralityof long tapes each of which is of sufficient length to completely coverthe elastomeric core when wrapped therearound; and wrapping one of saidtapes, without splicing to another tape, around the elastomeric core.